I have an Ibanez sr800. After lowering the bridge to its lowest the action still feels a bit high, especially compared to all the basses I played at guitar center.

Is there something else I can do to lower it?

Is the neck bowed inwards? If it is you usually need an Allan Key/Wrench to take out the bow (after you've first slackened the strings).
Lowering the strings will alter the intonation making it flat at the 12th fret when in tune with string played open

Take it to a shop and have them show you how to do it and then you'll have the info for the next time you change strings or need a setup on your SR800. If they fit and it won't turn there may be other issues involved.

__________________"I have suffered for my music and now it's your turn." Neil Innes

Yes there may be other issues. From what I read on this, it is not a higher line item, so you may have to accept its limitations.

If this is a Bolt on Neck, look into shimming the Neck to get the action lower. This is why I only play Bolt ons and my action is sub1mm High and Sub2mm on the Low B.

If you are played out on the Truss Adjustment, then heavier strings are not the way to go.

As you can see below, All I Play are Ibanez. Only Bolt Ons with Stringers.
(Iv'e had a Jackson, a US Custom BCRich Mockingbird, a $5K War...jksh$*^@#, and 2 other Ibanezes in the past.)

You can now get into what I think are the best production Basses ever, the Ibanez 400 and 450 Series BTB's for as little as $300 these days, 4, 5, and 6 Strings are out there. The Hardware leaves something to be desired, I will replace mine one day after I get another 456QM, but over all, stable, solid, and slammin.

I've got a beautiful G&L L2500 with a little too much bow, my problem is that the truss rod will not move either way, when I applied maximum pressure the Allen key twisted.
Going to get in touch with G&L to see how the rod is secured or will it be a finger board off job.